Daring Men in Seven Nations Aim to Harness GIANT Rockets (Aug, 1931)
Daring Men in Seven Nations Aim to Harness GIANT Rockets
FIFTEEN years ago the rocket was a toy, fit only for fireworks or laboratory demonstrations. Twelve years ago only one scientist in the world, the American physicist, Dr. Robert H. Goddard, of Clark University, Worcester, Mass., was working to transform this ancient plaything into a source of power for fast vehicles. So rapid has progress been, since then, that today the rocket is a young giant, though as yet too impetuous and uncontrolled for commercial use.
Scientists and daring men of seven countries, including the United States, are making serious and audacious tests that may soon solve the problems connected with this form of transportation.
A few weeks ago I visited the Raketenflugplatz at Berlin, the world’s most extensive experimental ground for the study of rockets. It lies in Reinickendorf, not five miles from the heart of the German capital, and sprawls northward into the hilly, tree-protected country surrounding the metropolis. At this plant, larger than the famous flying field at Tempelhof, six engineers are working seven days a week to accomplish the miracle of harnessing giant rockets.
The name Raketenflugplatz means “rocket flying field.” It was not without design for the future that the Verein fur Raumschiffahrt, the German society sup- porting these experiments, laid out so large a field. Within five years, the engineers there have predicted, rockets carrying mail will leave and arrive at the Raketenflugplatz on schedules, connecting all Europe by fast projectiles.
When this first objective has been safely accomplished, the workers of the German society will be ready to try a more ambitious project. . This will be the shooting of a mail rocket across the Atlantic, to land somewhere near New York, with a cargo of letters or valuable express.
Such transatlantic rockets will be the forerunners of great rocket ships built to carry crew and passengers. They will cross the ocean from New York to Berlin in an hour, or two hours at the most, rising through the thick lower atmosphere on wings like those of an airplane, then speeding through the upper part of their course, perhaps five hundred miles above the surface of the globe, at an estimated speed of 3,000 miles an hour.
The chief engineers of the Raketenflugplatz are Rudolf Nebel, Willy Ley, and Klaus Reidel. They have announced that transatlantic passenger flights will not content them. Supported by a society of more than 1,000 enthusiasts, these German engineers hope some day to launch from their rocket field a bullet-shaped craft destined for the moon or one of the planets. They see no theoretical reason why it cannot be done, though difficult mechanical problems raise many practical obstacles. But one by one, through the cooperation of rocketors and scientists all over the world, these are being overcome.
IT MUST not be assumed that, : because their project is the largest, the Germans are the only ones working on the rocket problem, or indeed that the Raketenflugplatz is the only place in Germany where experiments are under way.
At present there are groups and individuals working in Germany, Austria, France, Italy, Russia, Roumania, and the United States to solve the technical barriers to the use of this new engine. In each of these countries the program is essentially the sameâ€”first an altitude rocket that will go up fifty, a hundred, or two hundred miles, to the extreme limit of the earth’s atmosphere, driven by powerful liquid fuels and properly equipped with scientific apparatus and a parachute to bring both rocket and instruments safely back to earth. Then mail rockets, under control from start to destination, shooting between cities, bearing commercial traffic at enormous speeds, to be followed by rockets capable of crossing the oceans or encircling the world, carrying freight and passengers. Finally, powerful ships of space, roaring to the moon or to our other neighbors in interplanetary space.
As you read these words, the first high altitude rocket may be hurtling upward from any one of nearly, a; score of experimental stations here and abroad, penetrating into that borderline between atmosphere and space that no instrument made by man has so far touched. When that has been accomplished we may look for the rapid development of rocket traffic, for the greatest problem is that of applying tremendously powerful liquid fuels in such a way as to get the full energy without bursting the rocket.
The fuel at present being experimented with by the Germans consists of liquid oxygen and gasoline. The oxygen is necessary because the combustion is so rapid that it could not be supported by the oxygen of the air. The handling of the oxygen is one of the chief difficulties. To keep it liquefied it must be maintained at a temperature colder than 183 degrees below zero, Centigrade. At this temperature even mercury is frozen, and special, elaborate containers must be used to handle the liquid.
ABOVE this temperature the oxygen . boils furiously, giving off quantities of oxygen gas. If the container is closed to prevent free evaporation a tremendous pressure is created almost instantly, and if no provision is made to relieve it, the container will burst with a terrific explosion.
During the rocket’s flight the oxygen fuel must be kept cold, yet under sufficient pressure to force it rapidly into the combustion chamber, which is the motor of the rocket. There, not many inches from the extreme cold of the oxygen, a temperature as great as that of the oxy-acetylene flame exists, fed by continuous streams of gasoline and oxygen.
A most important problem, and one that has not been definitely settled in spite of the many experiments, is the best shape for the combustion chamber, and the materials from which it should be constructed. This chamber, which the Germans call the rocket motor, is the place in which the continuous driving explosions take place. From one end of it projects the slightly flaring nozzle through which rush the escaping gases.
The best shape so far discovered is cylindrical, with rounded ends, so that the inner chamber looks not greatly unlike an egg with both ends the same size. It has been learned that the fuel must be introduced at the lower end, near the exhaust nozzle, but in such a direction that it squirts upward, the streams of gasoline and oxygen meeting somewhere above the center.
ROCKET motors are now being built of aluminum or duralumin, with an inner lining of thin copper. They are surprisingly small for the power they yield, and this is one of their advantages, shared by no other’ motor. There are no moving parts, consequently no mechanical losses. A small rocket motor not much larger than an ordinary egg, weighing complete not much more than a quarter of a pound, will yield a “lift” of about twenty-five pounds, and can shoot a ten-pound rocket upward for twenty miles in little more than a minute.
It is difficult to calculate the actual horsepower generated by a rocket motor, since there is no revolving shaft from which the brake horsepower may be taken. Further, the faster a rocket goes the greater its efficiency. This theoretically approaches the maximum when the rocket motor is moving forward at the speed of the ejected gases. This may be in the neighborhood of a mile a second, and since to date no rocket has ever gone so fast, we must depend upon calculations alone to give us the horsepower generated by such an engine.
Dr. Paul Heylandt, a German experimenter, recently announced that he had built a rocket motor weighing fourteen pounds capable of delivering 200 horsepower. A gasoline motor of the same power would weigh between 250 and 350 poundsâ€”a comparison which shows the enormous advantage of rocket power in craft that require light engines.
Dr. Heylandt’s motor, attached to a specially constructed automobile, was tried out at Tempelhof air field. Burning a fuel consisting of liquid oxygen and gasoline, it emitted a roar that startled persons two miles away and sent the car forward at a terrific speed.
THE fact that vehicles such as automobiles and ordinary airplanes are structurally incapable of traveling at speeds sufficient to utilize the full efficiency of rocket motors may forever prevent the employment of this method of propulsion for such machines. Rocket vehicles will have to be streamlined to the last degree, perhaps shaped like military torpedoes.
In fact it was a ship of just this type that was recently described by Harold A. Danne, one of the aeronautical engineers in America who has given his attention to the problem. The transatlantic rocket ship will have a water-tight and air-tight cabin. The wings and landing gear will be drawn into the body when the craft is in full flight, and it will go roaring through the upper strata of the atmosphere at a calculated speed of 3,000 miles an hour or more, with a spear of bluish-white fire streaming out behind. These ships will have to be equipped with special navigating apparatus, probably devices like modern compensating artillery gun sights, to permit steering by the fixed stars.
Such flyers will make the journey from New York to Paris in an hour or an hour and a half. Los Angeles will be only about an hour away from New York. Commuters from San Francisco can go daily to their jobs in Chicago.
Before these wonders come to pass, however, a stupendous amount of work must be done. We are still in the first stage of rocketry, and a large portion of the work is now being done not with actual rockets, but on what technicians call the “proving stand” â€”a set-up on which rocket motors can be tested as to lift and efficiency without going to the trouble or expense of building the entire rocket. Less spectacular than actual rocket shots, the proving stand work is nevertheless extremely important at this stage.
LIQUID fuel rockets consist of three parts J â€”the tanks for fuel together with the necessary feed lines and valves, the motor or combustion chamber and its nozzle, and the “pay-load” compartment, which in small rockets includes the instruments, such as the barometer, thermometer, and camera sent up to record a picture of conditions at high altitudes, and the parachute or other landing gear.
Each part presents innumerable unsettled problems. The tanks must be arranged so as to give the rocket complete balance in flight, whether they are full or empty and in all stages between. The pay-load must be light, compact, and able to withstand shocks, and its compartment must be so placed as not to disturb the balance of the rocket. The motor must be of just the proper size and shape to get the most out of the fuel that can be carried, else the rocket will fall short of its mark, or worse yet, explode.
At the German rocket flying field an elaborate technique has been worked out for making and testing rocket motors on the proving stand. This work is necessarily dangerous, and every precaution is taken to have all workers in safety behind embankments dur- ing tests. The fuels are turned on by remote control, and the lift of the rocket motor is automatically recorded by a special clockwork device.
A series of experiments along this same line will soon be started near New York by the American Interplanetary Society, the organization in this country that corresponds to the German society. Several individual Americans, particularly Dr. Robert H. Goddard, are also carrying on experiments with rockets. Dr. Goddard is now devoting his full time to rocket experiments at Roswell, N. M., under a grant of $100,000 made by the late Simon Guggenheim.
ANOTHER American at work on the problem of adapting liquid fuels to rocket motors is Harry W. Bull, of Syracuse, N. Y., a student at Syracuse University who gained international attention by his experiments with a rocket sled last spring. Bull is now making use of the laboratories of the university to develop a powerful rocket motor, and may later build a rocket making use of his discoveries.
These are by no means the only Americans who are working on this fascinating new problem in this country and abroad. In Vienna, the American physicist, Dr. Darwin O. Lyon, is reported to be building a new rocket, following the accident that destroyed his attempt at Mt. Redorta, in Italy, last year. Several universities and technical schools in this country have now begun to ‘ turn their attention to rockets, and it is likely that several students of engineering will make a mark for themselves in the near future with discoveries now on the way.
Americans must hurry if they are to compete in this field with the engineers of Europe. There are now four European groups organized to further rocket study, and all are headed by engineers, scientists, or mathematicians. The president of the German Verein fur Raumschiffahrt is Professor Hermann Oberth, internationally known rocketor. A new organization has recently been formed at Vienna under the leadership of Guido Baron von Pirque, one of the foremost engineers of Austria.
IN LENINGRAD there is a group headed by Professor Nikolas Rynin, mathematician and engineer, and in France a committee of members of the French Astronomical Society annually awards the international Rep-Hirsch prize of 10,000 francs for the furtherance of astronautics, as the new science of space navigation has been called. This prize is made possible by the interest and generosity of Andre Hirsch, the French banker, and Robert Esnault-Pelterie, author of L’Astronautique, an aeronautical engineer of international reputation.
Perhaps never before in the history of science, with the possible exception of radio, has a projected development of this kind attracted so much popular attention, or enlisted so many enthusiasts. In Europe more than 1,000 persons belong to the various societies and contribute regularly to the experiments. In this country we have not heard so much of rocketry, but already there are several hundred enthusiasts organizing to begin experiments on an important scale.
Perhaps the day of huge space-ships flying to the moon is still a considerable distance away, but it is reasonable to believe that persons now living will see rockets cross the ocean with freight, and perhaps even passengers. It is not impossible, with so many working on the problem, that all of these things will come even sooner than we think. Rockets may be crossing the ocean yet in this decade.